The present invention relates to a light source apparatus or an apparatus for generating ultraviolet and visible light rays utilizing microwave, which apparatus is suited for irradiating a large area.
As the apparatus for generating light by utilizing microwave (hereinafter also referred to as the light source apparatus) known heretofore, there can be mentioned a typical one disclosed in U.S. Pat. No. 3,872,349. In the case of this known light source apparatus, a lamp is disposed within an elongated cavity which is connected to a microwave generator. With this structure, microwave energy is transformed to plasma energy within the lamp and light is emitted. It is reported that the emission of light can take place even when the cavity is not in the resonant state. An advantage of this known light source apparatus can be seen in that no electrodes are required, which in turn means that the structure of the light source is extremely simplified. Besides, the useful life of the light source apparatus as a whole is lengthened significantly because of the absence of such problems as consumption of the electrode, emission of impurities from the electrode and the like. Further, the light source apparatus can enjoy a great freedom in the selection of substance or material with which the lamp is to be filled, because of no necessity of taking into consideration the reaction of the material with that of the electrode.
The lamp used in the prior known light source apparatus mentioned above is implemented in a linear or spherical configuration. It should however be mentioned that in the known light source apparatus, no consideration is paid concerning the irradiation of a large area. On the other hand, employment of the light source apparatus capable of irradiating a large area is often required in the specific fields typified by the process of manufacturing semiconductor devices. In reality, in the specific utilization field such as mentioned above, irradiation of a large area with high irradiance is often demanded.